doolittle



(No Model.) 3 SheetsSheet 1.

' W. W. DOOLITTLE.

OOLLAPSIBLE TAP.

No. 481,648. Patented Aug. 30, 1892.

(No Model.) 3 Sheets-Sheet 2.

' W. D00 TLE.

APSIB AP.

No. 481,648. Patented Aug. 30, 1892.

I d; l

1 g .imllllml Y 265565. %\mzzw I 5 (No Model.) 3 Sheets-Sheet a.

I W. W. DOOLITTLE.

J GOLLAPSIBLE TAP.

fidl 181,648 Patented Aug. 30, 1892.

DW/if 7%?[20/2; 7% Jan; 1%! 6nnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn c.

UNITED STATES PATE T cn.

WILLIAM WV. DOOLITTLE, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE CRANECOMPANY, OF SAME PLACE.

COLLAPSIBLE TAP.

SPECIFICATION forming part of Letters Patent No. 481,648, dated August30, 1892.

Application filed February 9, 1892- Serial No. 420.904. (No model.)

To all whom it may concern.-

Be it known that I, WILLIAM W. DOOLIT- TLE, a citizen of the UnitedStates, residing at Chicago, in the county of Cook and State ofIllinois,have invented certain new and useful Improvements in Collapsible Taps,which are fully set forth in the following specification, referencebeing had to the accompanying drawings, in which Figure 1 represents aside elevation of a tap embodying my invention; Fig. 2, a front endelevation of the same in working adjustment; Fig. 3, a longitudinalvertical section of the same, taken on the line 3 3 of Fig. 2; Fig. t, a

cross-section taken on the line 4 4: of Fig. 3, looking in the directionof the arrow and in working adjustment; Fig. 5, a side elevation of thecutter-holder detached; Fig. 6, a vertical section of the same, taken onthe line 6 6 of Fig. 5; Fig. 7, a vertical section taken on the line 7 7of Fig. 1, and Fig. 8 a side elevation of one of the cutters detached.

My invention relates to that class of taps generally known ascollapsible that is, in

which the cutters are adjustable from their working position to aposition in which they lie somewhat within their former circumscribingcircle to provide for ready removal from their work and other purposes.

The invention consists in the construction and mounting of the cuttersand the devices whereby the collapsing adjustment is effected.

I will now describe in detail the construction and operation of a tap inwhich I have embodied my invention in one practical form and theparticular improvements constituting my invention, and which I desire tosecure by Letters Patent, will be more definitely pointed out in theclaims.

4 In the drawings, A represents What may be called the main head orholder of the tap, and B the cutter-head or holder, in which the cuttersare mounted and which itself is mounted in the main head A. The head Ais composed of a cylindrical cup a, at the back of which projects a stem(1. of much less diameter, by means of which the device is fastened tothe usual mandrel, this stem being shown provided with an aperture a 5by means of which the attachment is made.

The cutter-head B is solid and mainly of cylindrical form, but withdifferent diameters. The larger end I) of this head is adapted to fitneatly within the cup a of the holder, being in length about the same asthe depth of the cup. In front of this section the head isconsiderablyenlarged to form a ring or collar 1), the front portion of which is cutdown to make a smaller section of the collar 5 Then the extreme frontend b of the head is cut down to a diameter less than the rear endsection and is made slightly tapering, as seen in Fig. 1. In the surfaceof this cutter-head B a series of longitudinal grooves b is out, whichare intended for the reception of the cut- 'ters, and hence in numberare the same as the number of cutters desired. In the drawings fourareshown. These grooves run the entire length of the cutter-head and arecut through, so as to run underneath or within the central 7o collar 12as seen in Fig.6. They are circular in cross-section from the bottomnearly to the surface of the head; but are out out at the openingsomewhat so as to provide shoulders 19 for a little distance inward onthe end sections of the head, as seen in Figs. 4 and 6, the spacebetween which is preferably a little less than the diameter of thegrooves-that is, these grooves after passing said shoulders at theentrance open out a little way on each side on the arc of a circle,which is completed in the finishing of the groove. The cutters C areconstructed and adapted to be seated in these grooves in thecutter-head. They are in length the same as the length of the said headand are substantially cylindrical in cross-section, so that they can beslippedinto their seats underneath the central collar on thecutter-head. The tail end 0 of each cutter is, in fact, a cylinder of asize adapted to 0 fit the circular grooves in the cutter-head, with theexception of a longitudinal groove 0 made in one side thereof, which isconcave in cross-section. This groove in each cutter is in length aboutthe same as the depth of 5 the cupin the main head, so that when theparts are all mounted in working organization, as seen in Fig. 3, theseportions of the cutters will be inclosed within the cup. Commencingabout at the inner end of this groove 0 a depressed section c extendsoutward to the outer extremity of the cutter. At one side orin rear ofthis section of cutting-teeth the cylinder is cut outto'form a ratherdeep groove c extending the length of the toothed section, as seen inFig. 8, and being almost in line with the groove 0, while the line ofcutting-teeth is almost outside of the latter.

Within the cup of the main head there is set a series of ribs or splinesD, corresponding in number to the number of cutters. They are set in theinterior of the cup, preferably by means of dovetail seats or grooves ain the cup, adapted to receive a correspondinglyshaped bottom at of thesplines, and the outer portion of the latter projecting into the cup isrounded or circular, as seen at 01, whereby these splines are adapted tofit the respective grooves c in the tail ends of the cutters. These ribsor splines are arranged to correspond with the grooves in thecutter-head in which the cutters themselves are mounted, so that whenthe said head is placed within the cup one of these ribs will projectinto the opening of each of said grooves, and so is received into thegroove 0 in the cutter that is mounted in this particular seat, as seenin Fig. 4. Now the thickness of the ribs D is considerably less than thewidth of the openings of the grooves or recesses in the cutterhead.Evidently, then, there may bea differential movement between the mainhead and the cutter-head B within the limits thus provided, and it isobvious that this movement will oscillate the cutters in one directionor the other in their seats on account of the engagementof the splineswith said cutters. The efiect of this oscillation will be to project thecutting-teeth at the outer end of the out terl1ead a little beyond thesurface of said head in one position, while in the other they will bewithdrawn within the said circumference, as will presently be explained.The range of this movement between the main head and the cutter-head isdetermined by the shoulders b There is also a short circumferentialgroove 1) in the cutter-head, and a screw E is set into it from the sideof the cup to hold the head from movement lengthwise.

Owing to the position of the line of cutting-teeth on the cuttersomewhat within the circumference of the latter, as indicated in Fig. 3,when the head A is turned back, so as bring the stud E to the left endof the recess b, as seen in dotted lines in Fig. 4, the teeth will beturned down within the circumference of the front end of thecutter-head; but when turned in the other and working direction into theadjustment shown in full lines in Fig. at the cutting-teeth will beturned out, so as to project beyond the circumference of the head, asseen in Figs. 1 and 3, which is their working position, the head A beingrevolved for working in the direction indicated by the arrow in Fig. 4.It will be seen that this adjustment of the cutters will be effected bythe differential movement between the main head and the cutter-headwithin the limits of the shoulders b at the opening of the grooves andthrough the engagement of the splines D with the grooves c of thecutters. This movement may be obtained in different ways. In thedrawings the device by which it is produced is a friction-band F, whichis applied to the larger circumference of the central band or collar bthe ends f of which are bent outward horizontally and parallel to eachother and are fastened together by a screw-bolt G. A straight stationarybar If is extended along a little outside of the tap and parallel withthe axis thereof, and the fork provided by the projecting ends of thefriction-band is arranged to embrace this bar. The band is tightenedupon its seat by means of the bolt,so as to produce friction sufficientto hold the cutter-head stationary while the main head continues torevolve in one direction or the other during the limited period purposeof adjusting the cutters in and out,

as required, these cutters being turned out t into working position whenthe tap is revolved in the direction indicated by the arrow in Fig. 4and turned in or collapsed when the movement is reversed, so that thetap may be withdrawn from the work, as usual. It will be noticed thatonly a short length of the toothed end of the cutters is exposed, and

it will be understood that in the ordinary work of tapping-machinesonlya short section of the cutting-teeth is brought into operation. Nowwith the long cutters here shown provided with a long toothed sectionthe cutters may be used much longer than usual by simply adjusting themforward. This is accomplished by simply setting a block or blocks behinda cutter in its seat, when of course it will be thrust forward in thelatter, thus bringing a new section of teeth into working position; butthe cutters are held in place by passing under the central collar on thehead and by a disk I, fastened to the outer end of the head and providedwith a flange 2', extending out a little over the outer ends of thecutters, as seen in Fig. 3. This disk is shown fastened to the end ofthehead by a screw 2''. When the teeth are worn down, the cutters areremoved and the worn sections cut oif, when they are replaced in theirseats and blocks of suitable size put behind them to bring the teethinto working position. It will be seen that with this provision foradjustment the cutters may be used until the entire length of thecutting-sections has been used up.

The particular device foreifectin g the difierential movement, wherebythe adjustment of the cutters is obtained, as described above,

may be varied, and I do not wish to be un derstood as limiting myself tothe particular device here shown and described. There may be changes inother particulars of construction also without departing from the mainfeatures of this invention, and such changes I contemplate in practice.

Having thus described my invention, what I claim as new, and desire tosecure by Letters Patent, is

1. In a collapsible tap, the main head A, in combination with thecutter-head B, mounted within the former and having a limited freemovement therein, the cutters C, mounted in the head B in seats in whichthey are free to oscillate, a connecting device between said cutters andthe main head, and a friction device applied to the cutter-head, wherebya limited differential movement between the main head and the latter isobtained, substantially as described.

2.. In a collapsible tap, the main head A, provided with a cylindricalcup at, in combination with the cutter-head B, provided with circularlongitudinal grooves 19 the cylindrical cutter 0, provided with groovesc, the

splines D, set in the cup of the main head and engaging with the saidgrooves in the cutters, and means for connecting the main head with thecutter-head, whereby a limited diiferential movement is permitted,substantially as described.

3. In a collapsible tap, the cutter-head 13, consisting of thecylindrical section b, the enlarged central collar-section b, and thefront tapering section b and having longitudinal grooves 13 running itsentire length and passing underneath the central collar, in combinationwith the cylindrical cutters C, seated within the said grooves andadjustable lengthwise therein, and the flanged disk I, retaining thecutters in their seats, substantially as described.

4. In a collapsible tap, the main cup-shaped head A, in combination withthe cutter-head B, provided with longitudinal grooves, the cylindricalcutters O, mounted in said grooves and provided with the shortlongitudinal grooves c, the splines D on the inside of the cup, engagingwith said grooves in the cutters, the stop-stud E, arranged to play inthe cross-recess b of the cutter-head, and frictionband F, applied tothe cutter-head and fixed in position by any suitable device,substantially as described.

5. In a collapsible tap,the cup-shaped head A, in combination with thecutter-head 13, provided with longitudinal grooves 13 and shortcross-recess b and having an enlarged central collar b the cylindricalcutters O, seated in the head 13 and provided with grooves c at theirrear ends, the splines D on the internal surface of the cup, thestop-stud E, set into the side of the cup, and friction-band F, ap-

plied to the collar 1) and having its endsf turned outward horizontally,and the fixed bar H, arranged between the projecting ends of the band,substantially as described.

6. In a collapsible tap, a cylindrical cutter 0, provided with a section13 of cutting-teeth slightly within the circumference, and a groove 0extending the length of the said section and at the back thereof, incombination with a cutter-holder in which said cylindrical cutters arefree to oscillate and mechanism whereby in the backward movement of thetap the cutters are oscillated backward out of working position,substantially as described.

WVILLIAM W. DOOLI'ITLE. Witnesses:

A. M. BEST, WM. 0. CORLIES.

